A Flash Memory is a non-volatile memory and is characterized by that data is not lost when power is turned off, and therefore, is widely used as an external memory and an internal memory. For example, a solid-state disk (SSD) that is increasingly used in a computer system in recent years is implemented based on the flash memory. A SSD may also be called a solid-state drive. The flash memory is characterized by the limited number of times of erasure. Each read/write operation (which may also be called an erase operation) from/to the SSD wears the SSD to a certain extent.
To meet a requirement for massive data storage, it is generally required to form an SSD storage array with multiple SSDs. Wear leveling is a concept proposed for the SSD storage array, and is essentially making wear conditions of all SSDs in the SSD storage array similar and preventing certain SSDs from being erased too frequently. However, the wear leveling may result in a situation that multiple SSDs fail concurrently, thereby causing data loss.